Banana Joe - something for you to consider. If you have SEP and MEP you will get both of those on your 61.75 Certificate.
61.75 can give you everything you already have. MarkerInbound knows a lot more about this stuff than me. But I am curious, so did a bunch of quick googling. I get the impression that your type rating would let you fly 737s as a private pilot, but not go rent a Seminole - because there's no Multi-Engine Piston rating on your EASA license. Not meaning to slight Marker, I'm looking forward to learning more.
Here's my suggestion
You are spending a lot of money. A few more dollars won't matter if you come out ahead.
1. Find a flight school/FBO that will let you rent their twin.
2. Study for and pass the private pilot and instrument rating knowledge tests. Pass the commercial airplane pilot knowledge test.
3. Start flight training for the ME commercial certificate. Take the Private Pilot ME checkride. Now now you have a private pilot certificate independent of 61.75 and the rest of your training is PIC under FAA rules.
4. Prepare for the instrument rating in the twin and take a checkride. This is all PIC time under FAA rules.
61.129 has specific requirements including dual and solo cross country flights and IFR training. Work these into the training plan from the beginning.
5. Complete the flight training requirements for the commercial pilot certificate. Take the checkride including IFR approaches. Now, you have an FAA commercial pilot certificate with real instrument rating. (An instrument rating under 61.75 only counts for IFR flights under that certificate.)
6. Continue to fly until you hit 30 hours or are broke.
Depending one where you take them, the written tests are $80-150. Checkrides cost about $600. With an advance plan you spend just a bit more, but leave with credentials in addition to the flight time.
Snags? In EASA-land if you are rated and an instructor is on board it's dual not PIC. Not the case in FAA-land. Ditto for an examiner.
61.129 lists ten very specific hours of required experience that may either all be performed solo (only you in the airplane) or "performing the duties of PIC" with an instructor on board. It's 10 of one or 10 of the other. No mixing of the two. I know 61.129 all too well as I just passed the checkride in March. The place I did my training encouraged me to do the flying solo. I had a private multi rating, but no solo time in a twin. It was a great confidence builder to go do all the solo flights. (You can read about the adventures/misadventures (gear failure, weather, etc) along the way at my blog
Terry Pitts | A different take on the world) Long intro - are you happy with "30 hours" or are you hoping for "30 hours PIC?"
(Private message me if you like and I'm happy to discuss where I did my training - Turbo Seminole $310/hour with dual G5s and ADSB)
Hope this has been helpful. When I spend lots of money on flying I like to maximize the gain(s)!